Octacyano and Oxo- and Nitridotetracyano Complexes of Second and Third Series Early Transition Metals

Abstract

This chapter presents a summary on the chemistry of octacyano complexes and oxo- and nitridocyano complexes of molybdenum, tungsten, niobium, tantalum, technetium, and rhenium, with emphasis on the structural and kinetic properties. The octacyano complexes of molybdenum and tungsten are stable and inert toward substitution reactions and are suitable for theoretical studies of redox reactions and application of the Marcus theory. The oxo- and nitridocyano complexes of MO(IV), W(IV), Tc(V) , Re(V), and Os(VI) are good candidates for kinetic studies of substitution reactions with both mono- and bidentate ligands and are of interest in view of the large variations in the observed reactivity. The octacyano complexes of MO(V) and W(V) find excellent use in the oxidation of organic substances that require a mild oxidizing agent. Derivatives of the dioxotetracyano complexes of Mo(IV) and W(IV) can take up dioxygen that leads to the activation of the O2 molecule. Thus, the complexes are candidates as catalysts in oxidation reactions with dioxygen as well as oxygen-transfer reactions. The stereochemistry of octacyano complexes is concerned with the d1 and d2 ions of niobium, molybdenum, and tungsten.